Yes, they're broken. They've been broken in this particular way for a couple of years now. There's no neat workaround. One spoiler paragraph sitting in lonely isolation is always fine, but combining them isn't so easy.
What you did to break it (aka what to avoid)
Your problem was that you wrote out two adjacent paragraphs:
>! one paragraph
>! another ...
Sometimes, when MathJax is added to a site when it's mature and has a lot of posts already, Stack Exchange staff chooses to use \$ delimiters instead of $. This is to prevent things like
There are a few decent options in the $10-$20 range.
being displayed as
There are a few decent options in the \$10-\$20 range.
There are a handful of other sites in ...
Because when we added MathJax to the site, Stack Exchange staff decided to use \$ as delimiters rather than $ because many posts would be impacted otherwise. They cite an analysis by one of our citizens:
There are 349 posts that contain dollar signs, more than twice my estimate for posts that might benefit from MathJax (162). 137 of the 349 contain 2 ...
As far as I can tell, comment shortcuts have been around since basically forever.
The [tour] link got added sometime soon before June 6, 2014 (officially confirmed on June 11†), a short while after our About page instead became a Tour, and references to it got renamed accordingly over the next few months. Before then, however, we used [about] to ...
Re order the tags:
>! <sub>subscript spoiler</sub> | normal spoiler
The line needs to start with >!. You can put subscript inside the spoiler, but you can't wrap the whole spoiler in subscript with <sub>>! spoiler</sub> like you were doing.
Good news, but please edit your old questions as we normally do.
I'm seeing a lot of edits come through that should probably be spaced out over time so that the active page isn't flooded.
Before you start editing, please review both how many have been done and how many you plan to do.